This invention is concerned with separation membranes containing substantial amounts of polyketone polymers.
This invention relates to porous polymer structures and a method of preparing the same. More particularly, this invention relates to microporous polymer structures that may be readily prepared and are characterized by relatively homogeneous, three-dimensional, cellular microstructures and to a unique, facile process for preparing microporous polyketone polymer structures.
A variety of techniques and types of microporous membranes are taught in U.S. Pat. No. 4,247,498.
It has now been discovered that polyketone-based polymer may be rendered microporous.
The general class of polymers of carbon monoxide and one or more ethylenically unsaturated hydrocarbons has been known for some years. Brubaker, U.S. Pat. No. 2,495,286, produced such polymers of relatively low carbon monoxide content in the presence of free radical catalysts such as benzoyl peroxide. British Pat. No. 1,081,304 produced such polymers of higher carbon monoxide content in the presence of alkylphosphine complexes of palladium as catalyst. Nozaki extended the process to arylphosphine complexes of palladium. See, for example, U.S. Pat. No. 3,694,412.
More recently, the class of linear alternating polymers of carbon monoxide and unsaturated hydrocarbons, now known as polyketones, has become of greater interest, in part because of improved methods of production. Such methods are shown by European Patent Applications Nos. 0,181,014 and 0,121,965. The disclosed processes employ, inter alia, a compound of a Group VIII metal such as palladium, an anion of a non-hydrohalogenic acid having a pKa below 2 and a bidentate ligand of phosphorous. The resulting polymers are generally high molecular weight thermoplastic polymers having utility in the production of articles such as membranes for a wide variety of end uses.
U.S. Pat. Nos. 3,689,460 and 3,694,412 disclose two other processes for preparing polyketones. The catalysts described therein are complexes of a palladium, chloride or allyl palladium chloride and two trihydrocarbyl phosphine monodentate-like ligands, such as triphenylphosphine.
Another process for preparing polyketones is discussed by Sen and Li in an article entitled "Novel Palladium (II)-Catalyzed Copolymerization of Carbon Monoxide With Olefins", J. Am. Chem. Soc. 1982, 104, 3520-3522. This process generates higher yield than the other disclosed processes.
Yet another process for preparing polyketones is disclosed in a currently copending U.S. patent applicaton Ser. No. 908,899, filed Sept. 18, 1986. The process of the copending application is directed towards a preparation of polyketones to obtain a high yield, wherein a mixture of carbon monoxide and alkenically unsaturated hydrocarbon is polymerized in the presence of a Group VIII metal catalyst containing ligands, wherein hydrocarbon groups are bonded to an element from Group Va, characterized in that, as catalyst, a complex compound is used that is obtained by reacting a palladium, cobalt or nickel compound, a bidente ligand of the general formula: EQU R.sub.1 R.sub.2 --M--R--M--R.sub.3 R.sub.4,
in which M represents phosphorous, arsenic or antimony, R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are identical or different hydrocarbon groups, and R represents a divalent organic bridging group having at least two carbon atoms in the bridge, none of these carbon atoms carrying substituents that may cause stearic hindrance, and an anion of an acid with a pKa of less than two, provided the acid is neither a hydrohalogenic acid nor a carboxylic acid.
Polyketones have generally not been used as separation membranes. The excellent strength, good solvent resistance, high melting point and hydrophilic nature of the polyketone polymers make them suitable for microfiltration applications.
Certain novel microporous polyketone-based polymers of the present invention are characterized by being non-continuous and having a narrow cell size distribution, as determined by electron microscopic analysis.